feat: add Tencent GooseFS Table Master namespace implementation (Python)

Summary

Add a new Lance Namespace implementation backed by Tencent Cloud GooseFS Table Master to the Python lance-namespace-impls package.

GooseFS Table Master is a Lance-native metadata service exposed over gRPC. Unlike general-purpose catalogs (Hive, Glue, Iceberg, Polaris, Unity), it is purpose-built for Lance — every registered table is a Lance table, so no table_type=lance marker filtering is required on the client side.

The new implementation acts as a thin pass-through layer that translates each Lance Namespace request into the corresponding *PRequest defined in the GooseFS Table Master gRPC schema and forwards it through the official goosefs-metastore-client library.

Motivation

• Provide first-class Lance Namespace support for users running Lance on top of Tencent Cloud GooseFS / COS.
• Cover the full Lance Namespace surface (basic CRUD + advanced operations such as indexing, tags, versioning, and transactions) without the overhead of mapping into a generic catalog model.
• Match the integration pattern already established for Hive, Glue, Iceberg, Polaris, and Unity.

Scope

Core implementation

• New GooseFSNamespace class registered as "goosefs" in LanceNamespaces
• 2-level namespace hierarchy (database > table); identifier is forwarded verbatim to the Table Master
• Configurable connection (uri / host / port / timeout / max_retries), authentication (authentication_enabled / username / impersonation_user), and namespace-level defaults (manifest_enabled / dir_listing_enabled)

Operations covered

• Namespace: Create / List / Describe / Drop / Exists
• Table: Create / CreateEmpty / Declare / Register / List / Describe / Drop / Deregister / Exists / Rename
• Data plane: Insert / MergeInsert / Delete / Update / Query / CountRows
• Schema evolution: AddColumns / AlterColumns / DropColumns / UpdateSchemaMetadata
• Indexing: CreateIndex / CreateScalarIndex / ListIndices / DescribeIndexStats / DropIndex
• Tags & versioning: Create/Update/Delete/List/Get tag, Create/List/Describe version, Restore, plus Batch variants
• Transactions & query planning: AlterTransaction / DescribeTransaction / ExplainQueryPlan / AnalyzeQueryPlan / GetTableStats

Packaging & build

• New optional extra goosefs in python/pyproject.toml (goosefs-metastore-client==0.1.7, grpcio>=1.78, grpcio-status>=1.78)
• New Makefile targets: lint-goosefs, install-goosefs, test-goosefs, integ-test-goosefs
• Unit tests: python/tests/test_goosefs.py
• Integration tests: python/tests/test_goosefs_integration.py

Documentation

• New page docs/src/goosefs.md describing background, configuration properties, object mapping, Lance-table identification, and per-operation semantics
• docs/src/.pages updated to include Tencent GooseFS: goosefs.md in the navigation

Out of Scope

• A Java implementation — this PR only adds the Python binding. A Java counterpart can be added in a follow-up if there is demand.
• Bundling the GooseFS gRPC .proto files in this repo; they continue to ship inside goosefs-metastore-client.

Verification

• ruff format --check and ruff check pass on the new files and across the whole python/ tree
• python -m compileall succeeds for src/ and tests/
• Unit tests in tests/test_goosefs.py pass with the goosefs extra installed
• Integration tests in tests/test_goosefs_integration.py pass against a live GooseFS Table Master (skipped automatically when the service is not reachable)

Compare the existing Hive, Glue, Iceberg, Polaris, and Unity implementations before working in the Python lance-namespace-impls package. Review python/pyproject.toml, python/tests/test_goosefs.py, python/tests/test_goosefs_integration.py, docs/src/goosefs.md, and docs/src/.pages; done means the GooseFS registration, operations, packaging, documentation, linting, unit tests, and integration checks are complete.